Mix the 500g flour, 5g yeast, 3 teaspoons sugar, 2 teaspoons vegetable oil and 1 cup of clear water in a bowl to make a dough. And knead it until surface smooth. Ferment it at room temperature for 1 hour. Then put it in the refrigerator overnight.
Soak the vermicelli in the warm water for more than 10 minutes until it becomes soft. Drain it and set aside.
Heat a wok with oil, and stir-fry the tofu until both sides of it become golden. Add ginger, garlic and vermicelli. Stir-fry a few times.
Add the 1/3 tablespoon dark soy sauce, 2 tablespoons light soy sauce, 1 tablespoon laoganma, 3 teaspoons salt, 1 teaspoon chicken essence and 200g water in the wok. And cook it until the sauce has thickness. Transfer it in a bowl and cool it.
Remove the dough the next morning, let it warm at room temperature for a while.
Add some flour and knead the dough until without pores in it. And set aside for a while.
Cut the dough into 16 small doughs. Press the dough into a 4mm thick skin with a rolling pin.
Scoop about 1 tablespoon of vermicelli filling and place it in the center of the wrapper. Wrap the filling into a bun.
Put the buns in the steamer and ferment it for 20 minutes.
1Heat the steamer with cold water. Cook the buns under middle heat for 10 minutes. Then, turn off the fire, and wait for 5 minutes. Transfer it on a plate and serve.